This invention relates to dispensing volatile materials such as insecticides, insect repellents, and fragrances. More particularly, it relates to devices containing a volatile material which are employed in conjunction with an electrical heating apparatus.
It is known in the art to impregnate a solid porous mat with a volatile material, or to place a volatile material in a pan-like metal structure. These mats and pans were placed on heaters to cause the volatile material to vaporize into the atmosphere. One type of heater used for this purpose was sold by S. C. Johnson & Son, Inc. under the trademark FUYI VAPE. See also U.S. Pat. No. 4,439,415 for a general discussion of heater units used for this purpose. The disclosure of this patent, and of all other publications referred to herein, are incorporated by reference as if fully set forth.
A problem with such metal pans is that for typical heaters they could cause the volatile material to be exposed to too much heat. This could cause the volatile to be used up too fast or to degenerate (particularly during extended usage).
The mats had similar problems, and also had significant problems with respect to the mats being exposed to different temperatures across the mat surface. In this regard, low-cost existing heaters often have hotter regions at certain points along their burner surface. The mats therefore had somewhat inefficient vaporization.
The above problems are of increased concern for products designed for use for a week or more. Merely adding additional volatile does not adequately address the problem as prolonged exposure of volatiles to too high temperatures wastes and/or destroys the volatile.
Another design consideration is that existing heaters, for safety and other reasons, often only accept inserts having a small cross-sectional shape (which fit into a small heater opening). Thus, any solution to the above problem needs to take into account size restrictions.
As such, it can be seen that a need exists for an improved volatile dispensing device.